JP7567553B2 - container - Google Patents

Description

The present invention relates to a container consisting of a cup having a lid.

Conventionally, containers such as paper cups have used a laminate in which a sealant layer is provided on a paper base material, and polyethylene (PE) resin has mainly been used for the sealant layer from the viewpoint of ensuring heat sealability and flexibility of the laminate.
Recently, there has been a demand for such containers to be heated in a microwave oven, but the heat resistance of the laminate with the above-mentioned polyethylene resin as the sealant layer is insufficient. Therefore, a paper cup has been proposed in which a polypropylene resin, which has higher heat resistance than polyethylene resin, is used as the sealant layer (for example, Patent Document 1).

JP 2003-95350 A

However, when the opening of the paper cup described in Patent Document 1 is closed with a lid material that can be opened by heat sealing, there are cases where the closed lid material cannot be peeled off from the opening or the paper peels off.

The object of the present invention is to provide a container and a lid having good peeling properties in order to solve the above problems.

The present invention solves the above problems by the following means. Note that, for ease of understanding, the following description will use symbols corresponding to the embodiments of the present invention, but the present invention is not limited to these.

The first invention relates to a container (1) comprising a cup (10) having a body (11) and a bottom (12), and a lid (20) for closing an opening provided in the body, wherein the body and the bottom are made of a first laminate (100) having a first paper base layer (101) and a first sealant layer (102) provided on at least one side of the first paper base layer, the opening of the body is provided with a flange portion (13) formed by folding back the first laminate so that the first sealant layer is exposed, and the lid is made of a base layer (201) and a sealant layer (102) provided on at least one side of the base layer. the container has as its constituent material a second laminate (200) having a sealant film layer (202) and a base layer (202A) joined to the flange portion, the sealant film layer having a base layer (202A) and a second sealant layer (202B) joined to the flange portion, the first sealant layer contains a polypropylene-based resin and has an MFR value of 15 g/10 min or more and 60 g/10 min or less, the base layer is made of a polyethylene-based resin, and the second sealant layer is mainly composed of a polyethylene-based resin and contains a tackifier or a polystyrene-based resin.
It is.

The second invention is the container (1) of the first invention, characterized in that the base layer (201) of the second laminate (200) is a second paper base layer, and the second paper base layer accounts for more than half of the total mass of the lid material.

The third invention is the container (1) of the first or second invention, characterized in that the sealing strength between the flange portion (13) of the cup and the lid material (20) is 8 kPa or more.

The fourth invention is a lid material (20) that closes the opening of a cup (10), the lid material is made of a second laminate (200) having a second paper substrate layer (201) and a sealant film layer (202) provided on one side of the second paper substrate layer, the sealant film layer has a base layer (202A) and a second sealant layer (202B) that is bonded to the opening, the base layer is made of a polyethylene-based resin, the second sealant layer is mainly composed of a polyethylene-based resin and contains a tackifier or a polystyrene-based resin, and the second paper substrate layer accounts for more than half of the total mass of the lid material.

The present invention provides a container and a lid having good peeling properties.

FIG. 2 is a perspective view of a container according to an embodiment. FIG. 2 is a cross-sectional view of a lid and a cup heat-sealed to a flange portion. FIG. 2 is a diagram illustrating a layer structure of a first laminate used in a cup. FIG. 2 is a diagram illustrating the layer structure of a second laminate used in the lid material.

The container having a lid material of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of a container according to an embodiment.
FIG. 2 is a cross-sectional view of the lid and cup heat-sealed to the flange portion.
Note that the following figures, including Fig. 1, are schematic views, and the size and shape of each part are appropriately exaggerated for ease of understanding. Also, as described below, the body 11 and the lid 20 are composed of a first laminate and a second laminate having multiple layers, but Fig. 2 shows only the layer structure of the body 11 and the lid 20, which are the first sealant layer 102 and the second sealant layer 202B located on the inner side of the cup, and omits the other layers.

(container)
1, the container 1 includes a cup 10 and a lid 20, and can accommodate contents such as food in the container portion of the cup 10 and seal with the lid 20. The container 1 of this embodiment can heat and cook the contents accommodated in the cup 10 while still in the cup 10 by using a microwave oven. For this reason, the cup 10 and the lid 20 are each made of a heat-resistant material so as not to cause phenomena such as foaming or melting when heated.

(Cup 10)
The cup 10 is a vessel formed into a truncated cone shape, and is composed of a body 11, a bottom 12, and a flange 13. The body 11, bottom 12, and flange 13 of the cup 10 are formed using a first laminate 100 including a first paper base layer 101 as a constituent material. Details of the first laminate 100 will be described later.
The body 11 is a cylindrical portion that forms the peripheral side surface of the truncated cone of the cup 10, with a bottom 12 disposed at one end edge of the cylinder and a flange portion 13 formed at the other end edge.
The bottom portion 12 is a member that constitutes the bottom portion of the cup 10 and is formed from a separate member from the body portion 11 .

The flange portion 13 is formed on the edge of the opening of the cup 10, and is formed by folding back the edge of the first laminate 100 constituting the body portion 11 towards the outside of the cup 10, as shown in Fig. 2. Therefore, the flange portion 13 is formed integrally with the body portion 11.
In this way, by providing the flange portion 13 on the body portion 11, it is possible to increase the rigidity of the opening of the cup 10 and to prevent the cup 10 from being deformed when carrying the cup 10. Furthermore, by providing the flange portion 13, it is possible to easily join the lid member 20 to the cup 10.
Here, a first sealant layer 102 (described later) is provided on one surface of the first laminate 100, and the first laminate 100 constituting the body 11 and the bottom 12 is disposed such that the first sealant layer 102 is located on the inner side of the cup 10, as shown in Fig. 2. Therefore, the first sealant layer 102 is exposed on the surface of the flange portion 13 formed by folding back the edge of the body 11.

(Covering material 20)
The lid 20 is a member that seals the opening of the cup 10, and is removably joined to the flange 13 provided on the cup 10. The lid 20 is formed using a second laminate 200 as a constituent material, and as shown in Fig. 2, is joined to the flange 13 of the cup 10 such that a second sealant layer 202B provided on one surface of the second laminate 200 is positioned on the cup 10 side. Details of the second laminate 200 will be described later.
Here, as described above, the first sealant layer 102 of the first laminate 100 is exposed on the surface of the flange portion 13, and this first sealant layer 102 is heat sealed to the second sealant layer 202B of the second laminate 200 that constitutes the lid material, so that the opening of the cup 10 can be peelably sealed by the lid material 20.

From the viewpoint of ensuring a more reliable bond between the lid material 20 and the cup 10 (flange portion 13), it is desirable that the bonding width t of the lid material 20 on the flange portion 13 in the cross section shown in FIG. 2 be 1 mm or more and 4 mm or less. If the bonding width t is less than 1 mm, the bonding area of the lid material 20 becomes too narrow, making it impossible to stably bond the lid material 20 to the cup 10, and reducing the sealing strength, which is undesirable. Furthermore, if the bonding width t exceeds 4 mm, the width dimension of the flange portion 13 must also be increased, which undesirably results in the outer shape of the cup 10 becoming too large. Furthermore, if the bonding area of the lid material 20 becomes too large, it may be difficult to peel off the lid material 20, which is undesirable.

(First laminate)
Next, the first laminate 100 constituting the cup 10 will be described.
FIG. 3 is a diagram illustrating the layer structure of the first laminate used in the cup.
The first laminate 100 is a component that constitutes the body 11, bottom 12, and flange 13 of the cup 10, and is formed by laminating, in order from the inner side of the cup 10, a first sealant layer 102, a first paper base layer 101, and a surface resin layer 103.

The first paper substrate layer 101 is a paper substrate that is the base of the first laminate 100, and can be, for example, uncoated paper, kraft paper, recycled paper of known origin, etc. From the viewpoint of good molding of the cup 10, the basis weight of the first paper substrate layer 101 is preferably 150 g/m ² or more and 350 g/m ² or less, and more preferably 180 g/m ² or more and 240 g/m ² or less. If the basis weight of the first paper substrate layer 101 is less than 150 g/m ² , the buckling strength of the molded cup cannot be obtained, and if a part of the cup breaks due to the pressing pressure when stacked, the cups become clogged and cannot be taken out, or the flanges are deformed by a slight drop, making handling difficult, which is not preferable. In addition, if the basis weight of the first paper substrate layer 101 is greater than 350 g/m ² , the curl processing of the flange portion cannot be stably processed at high speed, which is not preferable.

The first sealant layer 102 is the layer located on the innermost side of the cup 10, and has heat sealability, which is an adhesive property when heated. The first sealant layer 102 is mainly composed of polypropylene (PP) resin from the viewpoint of combining good heat resistance and heat sealability. Examples of the type of polypropylene resin used in the first sealant layer 102 include homopolypropylene, random polypropylene, and block polypropylene. Copolymer polypropylene in which a part of propylene is replaced with another monomer may also be used. In the present invention, it is preferable to use a homopolymer from the viewpoint of obtaining high heat resistance.
Furthermore, the MFR (melt flow rate) value of the polypropylene resin forming the first sealant layer 102 is desirably 15 g/10 min or more and 60 g/10 min or less, more desirably 30 g/10 min or more and 50 g/10 min or less, and even more desirably 35 g/10 min or more and 45 g/10 min or less.

If the MFR value is less than 15 g/10 min, when forming the first sealant layer 102 on the first paper base layer 101 by extrusion molding, the resin will have low fluidity when melted, and adhesion to the first paper base layer 101 will decrease, which is undesirable. Also, if the MFR value is greater than 60 g/10 min, a neck-in phenomenon will occur in which the extruded resin becomes narrower than the effective width of the die, making it difficult to form the first laminate 100, and phenomena such as foaming and melting during heating may occur, which is undesirable.

From the viewpoint of being heat-sealed without gaps by heating, the thickness of the first sealant layer 102 is desirably 15 μm or more and 50 μm or less, and more desirably 20 μm or more and 40 μm or less. If the thickness of the first sealant layer 102 is 15 μm or more, for example, when the body portion 11 is produced using the first laminate 100, the heat seal strength can be sufficiently maintained in the joining of the edges of the body portion 11. Also, sufficient pinhole resistance can be ensured.
Furthermore, by making the thickness of the first sealant layer 102 50 μm or less, it is possible to minimize the amount of plastic used while maintaining the stiffness of the original body roll. Furthermore, when creating blanks for the body 11 and bottom 12 by punching, it is possible to minimize the occurrence of burrs and punching defects.
For the first sealant layer 102, for example, PHA03A manufactured by SunAllomer Corporation, which is a homopolymer type polypropylene resin and has an MFR value of 42 g/10 min, can be used.

The surface resin layer 103 is the layer located on the outermost side of the cup 10, and protects the outer surface of the first paper base layer 101. The surface resin layer 103 also has heat sealability, which means adhesive properties when heated. From the viewpoint of preventing curling of the first laminate 100, the surface resin layer 103 is desirably formed of the same material as the first sealant layer 102, to the same thickness, and by the same method.
The outer surface of the first paper base layer 101 may be printed or the like. In this case, it is preferable that the surface resin layer 103 is transparent or nearly transparent so that the printed content can be visually confirmed.

(Second laminate)
Next, the second laminate 200 constituting the lid member 20 will be described.
FIG. 4 is a diagram illustrating the layer structure of the second laminate used in the lid material.
As shown in Figure 4, the second laminate 200 is formed by laminating, in order from the inner side of the cup 10, a sealant film layer 202, an adhesive layer 205, a first resin layer 203, an adhesive layer 205, a second paper base layer 201, an adhesive layer 205, a printing layer 206, and a second resin layer 204.

The second paper substrate layer 201 is a paper substrate that is the base of the second laminate 200, and can be, for example, uncoated paper, coated paper, or high-quality paper. In addition, the basis weight of the second paper substrate layer 201 is preferably 40 g/m ² or more and 100 g/m ² or less, and more preferably 70 g/m 2 or more and 90 g/m ² or less, from the viewpoint of ensuring flexibility as the lid material 20 that can be peeled off from the cup ^{10. If the basis weight of the first paper substrate layer 101 is less than 40 g/m 2 ,} the thickness of the lid material 20 is thin, which is undesirable because it curls in an unintended direction. In addition, if the basis weight of the first paper substrate layer 101 is greater than 100 g/m ² , the thickness of the lid material 20 becomes too thick, which reduces the flexibility of the lid material 20, and the workability of opening the container 1 is reduced, which is undesirable.
Here, the lid material 20 formed from this second laminate 200 is formed so that more than half of the total mass is accounted for by the second paper base material layer 201. This allows the lid material 20 (second laminate 200) to reduce the amount of fossil fuel used and reduce the environmental burden.

The sealant film layer 202 is the layer of the lid material 20 located closest to the cup 10. The sealant film layer 202 is a film in which a base layer 202A and a second sealant layer 202B are laminated in this order from the first resin layer 203 side. The sealant film layer 202 is bonded to the first resin layer 203 by, for example, a dry lamination method via an adhesive layer 205 made of a lamination adhesive. The lamination adhesive used may be a conventionally known adhesive, such as a urethane adhesive, an acrylic adhesive, or an isocyanate adhesive.
The base layer 202A is a base material that serves as the foundation of the sealant film layer 202, and may be made of, for example, a polyethylene-based resin, a polypropylene-based resin, or the like, with the use of a polyethylene-based resin being particularly desirable.

The second sealant layer 202B is the layer of the lid 20 closest to the cup 10, and has heat sealability, which is an adhesive property when heated. The second sealant layer 202B is mainly composed of a polyethylene resin, and further contains a tackifier or a polystyrene resin. Here, the main component refers to a component whose content in the target layer (here, the second sealant layer 202B) is 41% or more by mass, preferably 50% or more, and more preferably 60% or more.
Examples of the polyethylene-based resin include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). In addition to these homopolymers, copolymerized polyolefins in which part of ethylene is replaced with other monomers may also be used. Specifically, examples include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methyl methacrylate copolymer (EMMA). The content of the polyethylene-based resin in the second sealant layer 202B is preferably 41% by mass or more and 95% by mass or more.

Examples of the tackifier include aliphatic hydrocarbon resins including alicyclic hydrocarbon resins (alicyclic resins), aromatic hydrocarbon resins, rosins, polyterpene resins, and the like.
Examples of the aliphatic hydrocarbon resin include polymers mainly composed of monoolefins or diolefins having 4 to 5 carbon atoms, such as butene-1, butadiene, isobutylene, and 1,3-pentadiene; resins polymerized from cyclic monomers, such as resins obtained by cyclizing and dimerizing diene components in cyclopentadiene and spent C4 to C5 fractions and then polymerizing them; and resins obtained by intracyclic hydrogenation of aromatic hydrocarbon resins. Examples of the aromatic hydrocarbon resin include resins mainly composed of vinyl aromatic hydrocarbons, such as α-methyltoluene, vinyltoluene, and indene. Examples of the rosins include rosin, polymerized rosin, rosin glycerin ester, hydrogenated rosin glycerin ester, polymerized rosin glycerin ester, rosin pentaerythritol ester, hydrogenated rosin pentaerythritol ester, and polymerized rosin pentaerythritol ester. Examples of polyterpene resins include hydrogenated terpene resins, terpene-phenol copolymer resins, dipentene polymers, α-pinene polymers, β-pinene polymers, α-pinene-phenol copolymer resins, etc. Further examples of synthetic resin tackifiers other than those mentioned above include acid-modified C5 petroleum resins, C5/C9 copolymer petroleum resins, xylene resins, coumarone-indene resins, etc.
The polystyrene-based resin is a resin mainly composed of styrene, such as a homopolymer of styrene, a copolymer of styrene and acrylonitrile, methyl methacrylate, or the like, or a rubber-modified product thereof. Specific examples of the polystyrene-based resin include polystyrene, impact-resistant polystyrene (rubber-blended polystyrene), AS resin (SAN), ABS, and SMA (styrene-maleic anhydride polymer).
The content of tackifier or polystyrene-based resin in the second sealant layer 202B is preferably 1 to 30 mass %, and more preferably 2 to 15 mass %, because this makes it easier to obtain good adhesion to the substrate and suitable film-forming properties.

From the viewpoint of being heat-sealed without gaps by heating, the thickness of the second sealant layer 202B is preferably 5 μm or more and 20 μm or less, and more preferably 8 μm or more and 15 μm or less. If the thickness of the second sealant layer 202B is 5 μm or more, for example, when the lid material 20 is heat-sealed to the flange portion 13 of the cup 10, the bonding strength (sealing strength) between the flange portion 13 and the lid material 20 can be sufficiently ensured. In addition, by making the thickness of the second sealant layer 202B 20 μm or less, the amount of plastic used can be minimized, and the amount of fossil fuel-derived materials used in the lid material 20 can be reduced as much as possible.
Here, the sealing strength between the flange portion 13 and the lid material 20 is preferably 8 kPa or more in order to ensure sufficient airtightness by the lid material. If the sealing strength is less than 8 kPa, the airtightness by the lid material may be insufficient or a part of the lid material 20 may peel off from the flange portion 13, which is undesirable.

In addition, the sealant film layer 202 may have an intermediate layer having a predetermined function between the base layer 202A and the second sealant layer 202B. For example, by providing an intermediate layer, the adhesion between the base layer 202A and the second sealant layer 202B may be improved, or the overall thickness of the sealant film layer 202 may be adjusted. If the intermediate layer is to improve the adhesion between the base layer 202A and the second sealant layer 202B, it may be made of, for example, LLDPE or LDPE. If the overall thickness of the sealant film layer 202 is to be adjusted, it may be made of, for example, the same resin as the base layer 202A. Note that multiple intermediate layers may be provided according to the needs of the required functions, etc.

The first resin layer 203 is a resin layer provided between the second paper base layer 201 and the sealant film layer 202, and is, for example, composed of a PET resin film (thickness 12 μm), and this film is bonded to the second paper base layer 201 by a dry lamination method via an adhesive layer 205 made of a lamination adhesive. The first resin layer 203 can be made of the above-mentioned PET resin, polyester resin such as PBT resin, polyamide resin, polypropylene resin, etc. The first resin layer 203 is preferably a stretched plastic film, and more preferably a biaxially stretched plastic film, and for example, a biaxially stretched PET film, a biaxially stretched PBT film, OPP, ONY, etc. can be used.
The thickness of the first resin layer 203 is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 12 μm or more. The thickness of the first resin layer 203 is preferably 50 μm or less, more preferably 25 μm or less. If the thickness of the first resin layer 203 is less than 5 μm, the processability in the bonding process with other materials is poor, and even if bonding is possible, the resin will peel off or break in the subsequent process or during use, making it impossible to function as a lid material, which is not preferable. If the thickness of the first resin layer 203 is greater than 50 μm, it is not preferable because the heat is difficult to propagate, the stable area of the seal is narrowed, or the rigidity of the resin is too strong, impairing the flexibility as a lid material.

The second resin layer 204 is a resin layer provided on the surface of the second paper base layer 201 opposite to the first resin layer 203, and is composed of, for example, a PET resin film (thickness 12 μm) similar to the above-mentioned first resin layer 203. The second resin layer 204 is bonded to the second paper base layer 201 by a dry lamination method via an adhesive layer 205 made of a lamination adhesive.
The second resin layer 204 can be made of the above-mentioned PET resin, polyester resin such as PBT resin, polyamide resin, polypropylene resin, etc. The second resin layer 204 is preferably a stretched plastic film, more preferably a biaxially stretched plastic film, and for example, a biaxially stretched PET film, a biaxially stretched PBT film, OPP, ONY, etc. can be used.
The thickness of the second resin layer 204 is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 12 μm or more. The thickness of the second resin layer 204 is preferably 50 μm or less, and more preferably 25 μm or less. If the thickness of the second resin layer 204 is less than 5 μm, it is not suitable as a printing base material because of poor dimensional stability, and is also low in strength, which is undesirable because it is poor in processability in the lamination process with other materials. If the thickness of the second resin layer 204 is greater than 50 μm, it is undesirable because heat is difficult to propagate, narrowing the stable area of the seal, or the rigidity of the resin is too strong, impairing the flexibility as a lid material.
In this way, by arranging the first resin layer 203 and the second resin layer 204 so as to sandwich the second paper base layer 201, when the second laminate 200 is formed into a sheet, the amount of resin present on the front and back of the second paper base layer 201 can be made approximately equal, and curling of the second laminate 200 can be significantly suppressed.
The second resin layer 204 is the layer located on the outermost side of the lid material 20, and protects the outer surface of the second paper base layer 201. In this embodiment, the second resin layer 204 has a printed layer 206 on its inner surface that displays information about the contents of the container 1. Therefore, the surface of the second resin layer 204 on which the printed layer 206 is provided is bonded to the second paper base layer 201 via the adhesive layer 205. It is desirable that the second resin layer 204 be transparent or nearly transparent from the viewpoint of making the printed content of the printed layer 206 visible.
In the above description, the printed layer 206 is provided on the inner surface of the second resin layer 204, but this is not limiting and the printed layer 206 may be provided on the outer surface of the second paper base layer 201. In this case, the second resin layer 204 is bonded to the printed layer 206 provided on the second paper base layer 201 via the adhesive layer 205.

Here, in order to improve the peeling characteristics of the lid material 20 with the cup 10, it is desirable that the sealant film layer 202 be formed mainly in one of the following ways.

(First embodiment of sealant film layer 202)
The sealant film layer 202 of the first embodiment has a two-layer structure in which a second sealant layer 202B and a base layer 202A are laminated in this order from the cup 10 side.
In this embodiment, the base layer 202A is preferably made of a polyethylene resin.
The second sealant layer 202B of this embodiment contains a tackifier with a polyethylene resin as the main component, from the viewpoint of ensuring a good balance between heat sealability with the first sealant layer 102 of the cup 10 (first laminate 100) and ease of peeling. The thickness of the second sealant layer 202B is preferably 15% to 35% of the thickness of the base layer 202A. If the thickness of the second sealant layer 202B is less than 15% of the thickness of the base layer 202A, the second sealant layer 202B will break when heat-sealing with the first sealant layer 102 of the cup 10, which is not preferable because good peeling properties cannot be obtained. In addition, if the thickness of the second sealant layer 202B is greater than 35% of the thickness of the base layer 202A, the material cost will be high, which is not preferable.

The polyethylene resin that is the main component of the second sealant layer 202B is preferably linear low density polyethylene (LLDPE). In this case, from the viewpoint of improving adhesion to the adherend, it is desirable for the MFR to be greater than 7 g/10 min.
The tackifier contained in the second sealant layer 202B contains at least one of an alicyclic resin and a rosin ester resin. In the present invention, the tackifier is added to the second sealant layer 202B to adjust the sealing property. It is preferable to use a tackifier consisting of a mixture of an alicyclic resin and a rosin ester resin. The tackifier is preferably contained in an amount of 1 to 30% by mass based on the total mass of the second sealant layer 202B.
In addition to the above materials, an anti-blocking agent, a slip agent, etc. may be added to the second sealant layer 202B.

(Second embodiment of sealant film layer 202)
The sealant film layer 202 of the second embodiment has a two-layer structure in which a second sealant layer 202B and a base layer 202A are laminated in this order from the cup 10 side.
The base layer 202A of this embodiment includes linear low density polyethylene (LLDPE) and low density polyethylene (LDPE), and preferably has a greater content of linear low density polyethylene (LLDPE) than low density polyethylene (LDPE).
In order to ensure a good balance between heat sealability with the first sealant layer 102 of the cup 10 (first laminate 100) and ease of peeling, the second sealant layer 202B in this embodiment contains a polyethylene (PE)-based resin as a main component, a polypropylene resin, and a polystyrene-based resin. In addition, the second sealant layer 202B is preferably made of, in order of decreasing content, a polyethylene-based resin, a polypropylene resin, and a polystyrene-based resin.
In addition to the above materials, an anti-blocking agent and a slip agent may be added to the second sealant layer 202B.

(Another Form of the Second Laminate)
The second laminate 200 may be provided with a barrier resin layer instead of the first resin layer 203. That is, the second laminate 200 may be provided with a sealant film layer 202, an adhesive layer 205, a barrier resin layer, an adhesive layer 205, a second paper base layer 201, an adhesive layer 205, a printing layer 206, and a second resin layer 204, which are laminated in this order from the cup 10 side. This allows the second laminate 200 to be provided with barrier properties against oxygen and water vapor. The barrier resin layer may be a film obtained by depositing a metal oxide onto a resin film such as PET. Examples of inorganic oxides that can be used in the deposition layer include aluminum oxide and titanium oxide, which are metal oxides of the above metals, as well as silica, which is an oxide of silicon (Si). In particular, for packaging, it is preferable to have a deposition film of aluminum oxide. An example of a film in which a metal oxide is deposited is IB-PET (thickness 12 μm) manufactured by Dai Nippon Printing Co., Ltd.

The second laminate 200 may omit the second resin layer 204 depending on the application of the lid material 20. That is, the second laminate 200 may be configured such that, from the cup 10 side, the sealant film layer 202, the adhesive layer 205, the first resin layer 203, the adhesive layer 205, the second paper base layer 201, and the printing layer 206 are laminated. In this case, since the amount of resin differs between the front and back of the second paper base layer 201, if the second paper base layer 201 is in a sheet-like form, curling occurs, making it difficult to use. However, if the second laminate 200 is wound and supplied and heat-sealed directly to the cup in-line, it can be used as a lid material in this form as well.

Furthermore, the second laminate 200 may omit the first resin layer 203 and use a substrate other than paper, i.e., a substrate layer made of resin, as the second paper substrate layer 201, depending on the application of the lid material 20. In this case, the second laminate 200 is formed by laminating, in order from the cup 10 side, a sealant film layer 202, an adhesive layer 205, a substrate layer, an adhesive layer 205, a printing layer 206, and a second resin layer 204.
In this case, the material of the base layer can be selected depending on the application, and a PET resin film (for example, 12 μm thick) or a biaxially oriented nylon film (for example, 15 μm thick) can be used.

(Selection of sealant film layer)
Next, the selection of the sealant film layer 202 provided on the second laminate 200 constituting the lid material 20 will be described. Eight types of test specimens (test specimens 1 to 8) having sealant film layers with different layer configurations and materials were prepared as test specimens corresponding to the lid material, and each test specimen was heat-sealed to the flange portion 13 of the above-mentioned cup 10, and the sealing state and peeling characteristics between the test specimen and the cup (flange portion) were evaluated. In this evaluation, the sealant film layer of the test specimen that was evaluated as being good in both sealing strength and peeling characteristics was applied to the lid material 20.

In each test specimen, the base layer side of the sealant film layer was bonded to a PET resin film having a thickness of 12 μm by a dry lamination method.
The first laminate 100 constituting the cup 10 uses cup base paper with a basis weight of 220 g/ ^m2 for the first paper base layer 101, and uses homopolymer type polypropylene resin (manufactured by Sun Allomer, PHA03A, MFR = 42 g/10 min) for the first sealant layer 102 and surface resin layer 103, each formed to a thickness of 20 μm on each side of the first paper base layer 101.

Each test specimen was heat-sealed to the flange 13 of the cup 10 at 150° C. or 160° C. for 1 second under a pressure of 0.3 MPa, and the sealing strength of each test specimen to the flange and the peeling characteristics of each test specimen after sealing when peeled from the flange were evaluated. Details of the sealant film layer used for each test specimen and the evaluation results are summarized in Table 1 below.
Here, as described above, if the sealing strength is 8 kPa or more, the lid material (test specimen) is sufficiently heat-sealed to the cup 10, and sufficient airtightness can be ensured. The sealing strength was measured using a sealing strength measuring device (SEAL TESTER FKT-100J, manufactured by Sun Scientific). Using the measuring device, a needle was inserted into the bottom 12 of the cup 10 to allow air to flow in, and the maximum pressure until rupture or air escape occurred in the heat-sealed portion between the cup and the lid material (test specimen) was measured. The measuring device had a pressure setting of 0.07 MPa, and the air flow rate was set so that a pressure of 0.013 MPa was applied for 10 seconds.
The peeling properties were evaluated by a subject's sensory assessment of whether the test piece heat-sealed to the cup could be peeled off with his or her hands with ease.

As shown in Table 1, the sealant film layer of specimen 1 is made of Easy Peel Film 7601EA with a thickness of 30 μm manufactured by Toray Advanced Film Co., Ltd., and has a two-layer structure in which a base layer and a second sealant layer are laminated in order. The base layer is made of polyethylene resin, and the second sealant layer is made of a resin in which a polybutene resin is added to a polyethylene resin. The peeling mode of specimen 1 is an "aggregation" type. Here, the "aggregation" type refers to a mode in which the specimen (lid material) and the cup are peeled off due to destruction inside the second sealant layer.
When heat-sealing was performed at 150° C. for specimen 1, the sealing strength was less than 8 kPa, and sufficient sealing strength was not obtained. Regarding the peeling properties, the adhesion of specimen 1 to the cup was too weak, that is, it was in a so-called temporary adhesion state.
Furthermore, even when heat-sealing the test piece 1 at 160° C. was performed, the sealing strength was less than 8 kPa, and sufficient sealing strength was not obtained. Regarding the peeling properties, the adhesion of the test piece 1 to the cup was too weak, that is, it was in a so-called temporary adhesion state.

The sealant film layer of specimen 2 is an easy peel film 7601ED manufactured by Toray Advanced Film Co., Ltd., with a thickness of 30 μm, and has a two-layer structure in which a base layer and a second sealant layer are laminated in this order. The base layer is made of polyethylene resin, and the second sealant layer is made of a resin in which a polybutene resin is added to a polyethylene resin. The peeling mode of specimen 2 is an "aggregation" type.
When heat-sealing was performed at 150° C. for specimen 2, the sealing strength was less than 8 kPa, and sufficient sealing strength was not obtained. Regarding the peeling properties, the adhesion of specimen 1 to the cup was too weak, that is, it was in a so-called temporary adhesion state.
Furthermore, even when heat-sealing test piece 2 at 160°C, the sealing strength was 8 kPa, which was sufficient. However, in terms of peeling characteristics, the adhesion of test piece 1 to the cup was too weak, and it was in a so-called temporary state.

The sealant film layer of the specimen 3 has a thickness of 30 μm and is a two-layer structure in which a base layer and a second sealant layer are laminated in order. A polyethylene resin is used for the base layer, and a resin containing a tackifier in a polyethylene resin is used for the second sealant layer. The sealant film layer of the specimen 3 corresponds to the first aspect of the sealant film layer 202 described above. The peeling mode of the specimen 3 is an "interface" type. Here, the "interface" type refers to a mode in which the specimen (lid material) and the cup are peeled off due to destruction at the bonding interface between the second sealant layer and the first sealant layer on the cup side.
When test piece 3 was heat sealed at 150°C, the sealing strength was 10 kPa, which was sufficient sealing strength, and the peeling characteristics were also good, as the test subject was able to easily peel test piece 3 from the cup.
In addition, when test piece 3 was heat sealed at 160°C, the sealing strength was 9 kPa, which was sufficient sealing strength, and the peeling characteristics were also good, as the test subject was able to easily peel test piece 3 from the cup.

The sealant film layer of specimen 4 has a thickness of 30 μm and is a two-layer structure in which a base layer and a second sealant layer are laminated in this order. A polyethylene-based resin is used for the base layer, and a resin containing a polyethylene-based resin, a polypropylene resin, a polystyrene-based resin, etc. is used for the second sealant layer. The sealant film layer of specimen 4 corresponds to the second aspect of the sealant film layer 202 described above. The peeling mode of specimen 4 is an "aggregation" type.
When test piece 4 was heat sealed at 150°C, the sealing strength was 9 kPa, which was sufficient sealing strength, and the peeling characteristics were also good, as the test subject was able to easily peel test piece 4 from the cup.
Furthermore, when heat-sealing test piece 4 at 160°C, the sealing strength was 10 kPa, which was sufficient, but the peeling characteristics were confirmed to be good, as test piece 4 could be easily peeled off from the cup by the subject. It was confirmed that some fibrous sealant material, so-called whiskers, remained on the peeled surface, but this was at a level that would not cause any problems in practical use.

The sealant film layer of specimen 5 is 50 μm thick and has a two-layer structure in which a base layer and a second sealant layer are laminated in this order. The base layer is made of polypropylene resin, and the second sealant layer is made of high-density polyethylene (HDPE) and polypropylene resin. The peeling mode of specimen 5 is the "cohesion" type.
When the specimen 5 was heat sealed at 150°C, the sealing strength was 8 kPa, which was sufficient. However, regarding the peeling properties, when the specimen 5 was peeled from the cup, it was confirmed that a part of the resin (polypropylene resin) of the first sealant layer provided on the flange of the cup remained on the specimen side (PP elongation).
Even when the test piece 5 was heat sealed at 160°C, the sealing strength was 11 kPa, which was sufficient. However, in terms of peeling properties, when the test piece 5 was peeled from the cup, it was confirmed that a part of the resin (polypropylene resin) of the first sealant layer provided on the flange of the cup remained on the test piece side (PP elongation).

The sealant film layer of specimen 6 is 50 μm thick and has a multi-layer structure in which a base layer, multiple intermediate layers, and a second sealant layer are laminated in this order. The base layer is made of high density polyethylene (HDPE), the intermediate layer is made of high density polyethylene (HDPE), and the second sealant layer is made of high density polyethylene (HDPE) and polypropylene resin. The peeling mode of specimen 6 is the "cohesion" type.
When test specimen 6 was heat sealed at 150°C, the sealing strength was 11 kPa, which was sufficient. However, when test specimen 6 was peeled from the cup, the test specimen tore and a part of it remained on the cup side, a phenomenon known as paper peeling, was confirmed.
When the test piece 6 was heat sealed at 160°C, the sealing strength was 14 kPa, which was sufficient. However, regarding the peeling properties, when the test piece 6 was peeled from the cup, it was confirmed that a part of the resin (polypropylene resin) of the first sealant layer provided on the flange of the cup remained on the test piece side (PP elongation).

The sealant film layer of the test specimen 7 is made of TAF650C manufactured by Mitsui Chemicals Tohcello Co., Ltd., with a thickness of 30 μm, and has a three-layer structure in which a base layer, an intermediate layer, and a second sealant layer are laminated in order. A special polyethylene resin is used for the base layer, a homopolymer type polypropylene resin is used for the intermediate layer, and a resin in which a polypropylene resin is added to a polyethylene resin is used for the second sealant layer. Here, the special polyethylene resin of the base layer is a polyethylene resin to which a polymer alloy (compatibilizer) is added, or a polyethylene resin to which a random type polypropylene resin is added, in order to structure adhesion with the homopolymer type polypropylene resin of the intermediate layer. The peeling mode of the test specimen 7 is a "coagulation" type.
When test specimen 7 was heat sealed at 150°C, the sealing strength was 9 kPa, which was sufficient. However, when test specimen 7 was peeled from the cup, the test specimen tore and a part of it remained on the cup side, a phenomenon known as paper peeling, was confirmed.
When test specimen 7 was heat sealed at 160° C., the sealing strength exceeded 15 kPa, which was sufficient, but in terms of peeling properties, test specimen 7 could not be peeled from the cup (not peelable).

The sealant film layer of specimen 8 is 9501E manufactured by Toray Advanced Film Co., Ltd., with a thickness of 30 μm, and has a two-layer structure in which a base layer and a second sealant layer are laminated in this order. The base layer is made of polypropylene resin, and the second sealant layer is made of a resin in which polypropylene resin is added to polyethylene resin. The peeling mode of specimen 8 is the "aggregation" type.
When test specimen 8 was heat sealed at 150°C, the sealing strength was 14 kPa, which was sufficient. However, in terms of peeling characteristics, when test specimen 8 was peeled from the cup, it was confirmed that a portion of the resin (polypropylene resin) of the first sealant layer provided on the flange portion of the cup remained on the test specimen side (PP elongation).
When test piece 8 was heat sealed at 160° C., the sealing strength exceeded 15 kPa, which was sufficient, but in terms of peeling properties, test piece 7 could not be peeled from the cup (no peeling possible).

The above evaluation results confirmed that the sealant film layers of test specimens 3 and 4 out of the eight test specimens, i.e., the first and second aspects of the sealant film layer 202 described above, had good sealing strength and peeling characteristics.

(Evaluation of sealing strength between lid and cup, and opening strength)
Next, the lids (Examples 1 and 2) having the sealant film layers of the above test specimens 3 and 4 were actually produced and heat-sealed to the flange portion 13 of the cup 10, and the sealing strength, opening strength, and peeling properties were evaluated. The evaluation results are summarized in Table 2 below.
The cup 10 used in the evaluation was the same as the cup used for selecting the sealant film layer described above. The lid materials of each of the examples and comparative examples used in the evaluation were heat-sealed to the flange portion 13 of the cup 10 by pressing at 0.3 MPa for 1 second at 150°C, 160°C, 170°C, or 180°C.

The sealing strength was measured by the same method as that used in the selection of the sealant film layer described above.
The opening strength is the force required to peel off the lid material heat-sealed to the cup. The opening strength was measured by using a force gauge (FGPX-5, manufactured by Nidec-Shimpo) to place the cup with the lid material facing up, and measuring the strength when opening when the peeling angle (angle with respect to the top surface of the lid material) was 45 degrees. In addition, a film chuck (6FC-20, manufactured by Nidec-Shimpo) was used as an attachment for the measurement. In general, an opening strength of 6.0 N or more and 18 N or less is sufficient for practical use. If the opening strength is less than 6.0 N, the lid material will be too easily peeled off from the cup, which is undesirable because it will cause problems such as the lid material peeling off unintentionally. If the opening strength is greater than 18 N, the lid material will not peel off from the cup, or even if it does peel off, the lid material or the cup may be damaged, which is undesirable.
The peeling properties were evaluated in the same manner as in the evaluation of peeling properties performed in the selection of the second sealant layer described above. A rating of "O" was given if the lid material could be easily peeled off from the cup, and a rating of "X" was given if the adhesion of the lid material to the cup was too weak or too strong and the lid material could not be peeled off.
The sealing strength and opening strength were measured using three lids from each Example and Comparative Example, and the average values were used as the measurement results.

The second laminate constituting each of the lid materials of Examples 1, 2, and the comparative example used in this evaluation is configured by laminating, in order from the inner side of the cup, a sealant film layer, a first resin layer, a second paper base layer, and a second resin layer.
Here, the first resin layer, the second paper base layer, and the second resin layer are configured in the same manner in Examples 1 and 2 and the comparative example. That is, the first resin layer is configured of a PET resin film having a thickness of 12 μm, the second paper base layer is configured of uncoated paper having a basis weight of 80 g/m ² , and the second resin layer is configured of a PET resin film having a thickness of 12 μm. The first resin layer, the second paper base layer, and the second resin layer in each example and comparative example are each bonded via an adhesive layer made of a lamination adhesive by a dry lamination method. In addition, a predetermined printing layer is formed on the second paper base layer side of the second resin layer.

The lid of Example 1 includes the sealant film layer (first aspect of the sealant film layer 202) used in the above-mentioned test piece 3. That is, the sealant film layer of Example 1 is formed of a two-layer structure having a thickness of 30 μm, in which a polyethylene resin is used for the base layer and a resin in which a tackifier is added to a polyethylene resin is used for the second sealant layer. The sealant film layer of Example 1 is bonded to the first resin layer by a dry lamination method via an adhesive layer made of a lamination adhesive.
As shown in the evaluation results in Table 2, the lid of Example 1 had a seal strength of 9.7 kPa and an open strength of 7.1 N when heat sealed at 150° C., confirming that it had sufficient seal strength and open strength. In addition, regarding the peeling properties, the subjects were able to easily peel the lid from the cup, confirming that there were no practical problems, and the evaluation was "good."
In addition, when heat sealed at 160°C, the sealing strength was 9.0 kPa and the opening strength was 7.3 N, confirming that the sealing strength and opening strength were sufficient. In addition, regarding the peeling properties, although a small amount of polypropylene resin on the cup side remained on the lid side, it was confirmed that the lid could be easily peeled off from the cup by the subject, and there was no problem in practical use, so the evaluation was "good".
When heat sealed at 170°C, the sealing strength was 9.0 kPa and the opening strength was 7.0 N, confirming that the sealing strength and opening strength were sufficient. In addition, regarding the peeling characteristics, the subject was able to easily peel the lid from the cup, confirming that there were no practical problems, and the evaluation was "good."
When heat sealed at 180°C, the sealing strength was 10.7 kPa and the opening strength was 8.4 N, confirming that the sealing strength and opening strength were sufficient. In addition, regarding the peeling characteristics, the subject was able to easily peel the lid from the cup, confirming that there were no practical problems, and the evaluation was "good."

The lid of Example 2 includes the sealant film layer (second aspect of the sealant film layer 202) used in the above-mentioned test piece 4. That is, the sealant film layer of Example 2 is formed of a two-layer structure having a thickness of 30 μm, in which a polyethylene resin is used for the base layer and a resin obtained by adding polypropylene resin, polystyrene-based resin, or the like to a polyethylene resin is used for the second sealant layer. The sealant film layer of Example 2 is bonded to the first resin layer by a dry lamination method via an adhesive layer made of a lamination adhesive.
The lid material of Example 2 had a seal strength of 7.3 kPa and an unseal strength of 6.5 N when heat sealed at 150°C, and was confirmed to have sufficient unsealing strength, but the seal strength was below 8 kPa and was confirmed to be insufficient. In addition, regarding the peeling properties, although the lid material could be peeled off from the cup by the subject, it was confirmed that the adhesion of the lid material to the cup was too weak and it was insufficient for use as a product, and the evaluation was "x".
However, when heat sealed at 160°C, the sealing strength was 8.0 kPa and the opening strength was 7.3 N, confirming that the sealing strength and opening strength were sufficient. Regarding peeling properties, although a small amount of polypropylene resin on the cup side remained on the lid side, the subject was able to easily peel the lid from the cup, confirming that there was no practical problem, and the evaluation was "good".
In addition, when heat sealed at 170°C, the sealing strength was 9.0 kPa and the opening strength was 8.0 N, confirming that the sealing strength and opening strength were sufficient. In addition, regarding the peeling characteristics, the subject was able to easily peel the lid from the cup, confirming that there was no problem in practical use, and the evaluation was "good".
When heat sealed at 180°C, the sealing strength was 9.7 kPa and the opening strength was 8.7 N, confirming that the sealing strength and opening strength were sufficient. In addition, regarding the peeling characteristics, the subject was able to easily peel the lid from the cup, confirming that there were no practical problems, and the evaluation was "good."

The comparative example of the lid material has a sealant film layer formed by co-extrusion of 10 μm of a blend resin of LDPE and α-olefin copolymer and 30 μm of a polyethylene resin in a first resin layer. That is, the sealant film layer in the comparative example is formed of a two-layer structure having a thickness of 40 μm, in which a polyethylene resin is used in the base layer and the above-mentioned blend resin (easy peel resin) is used in the second sealant layer.
The lid material of the comparative example had a seal strength of 2.7 kPa and an unsealing strength of 3.1 N when heat sealed at 150° C., which means that sufficient seal strength and unsealing strength were not obtained. Regarding peeling properties, although the lid material could be peeled off from the cup by the subject, the adhesion of the lid material to the cup was too weak and it was confirmed to be insufficient for use as a product, and the evaluation was "x".
In addition, in the case of heat sealing at 160°C, the sealing strength was 3.0 kPa and the opening strength was 3.1 N, neither of which were sufficient. Regarding the peeling properties, although the subject was able to peel the lid from the cup, it was confirmed that the adhesion of the lid to the cup was too weak and therefore insufficient for use as a product, and the evaluation was "x".
When heat sealed at 170°C, the sealing strength was 4.0 kPa and the opening strength was 3.5 N, neither of which were sufficient. Regarding peeling properties, although the subject was able to peel the lid from the cup, the adhesion of the lid to the cup was too weak and it was confirmed that it was insufficient for use as a product, and the evaluation was "x".
When heat sealed at 180°C, the sealing strength was 5.3 kPa and the opening strength was 5.0 N, which means that neither of the sealing strengths was sufficient. On the other hand, regarding the peeling properties, the subjects were able to easily peel the lid from the cup, and it was confirmed that there was no problem in practical use, so the evaluation was "good".

From the above, it was confirmed that the lid material of Example 1 had good sealing strength, opening strength, and peeling properties when heat sealed in the temperature range of 150° C. to 180° C. In addition, it was confirmed that the lid material of Example 2 had good sealing strength, opening strength, and peeling properties when heat sealed in the temperature range of 160° C. to 180° C.
In contrast, it was confirmed that the lid materials of the comparative examples were unable to provide sufficient sealing strength, opening strength, and peeling properties in any heat sealing temperature range.

REFERENCE SIGNS LIST 1 container 10 cup 11 body 12 bottom 13 flange 20 lid 100 first laminate 101 first paper base layer 102 first sealant layer 103 surface resin layer 200 second laminate 201 second paper base layer 202 sealant film layer 202A base layer 202B second sealant layer 203 first resin layer 204 second resin layer 205 adhesive layer 206 printed layer

Claims (3)

A container comprising a cup having a body and a bottom, and a lid for closing an opening provided in the body,
The body and the bottom are made of a first laminate having a first paper base layer and a first sealant layer provided on at least one surface side of the first paper base layer,
the opening of the body portion includes a flange portion formed by folding back the first laminate so as to expose the first sealant layer,
The lid material is made of a second laminate having a base layer and a sealant film layer provided on at least one surface side of the base layer,
The sealant film layer has a base layer and a second sealant layer bonded to the flange portion,
the first sealant layer contains a polypropylene resin, and the MFR value of the polypropylene resin is 30 g /10 min or more and 50 g /10 min or less;
The base layer is made of a polyethylene resin,
The second sealant layer is mainly composed of a polyethylene-based resin and contains a tackifier or a polystyrene-based resin;
A container characterized by: The base material layer of the second laminate is a second paper base material layer,
The container according to claim 1 , wherein the second paper base layer accounts for half or more of the total mass of the lid material. The sealing strength between the flange portion of the cup and the lid material is 8 kPa or more;
3. The container according to claim 1 or 2, characterized in that

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